A computational investigation has been carried out in some properties of Gabor lens with the aid of personal computer under the absence of space-charge effects. This work has been concentrated on designing two concentric, electrostatic and magnetic lenses. Electrostatic lens is a two-electrode immersion lens whose electrodes are cylindrical in shape separated by a separation distance. Magnetic lens is a number of turns of the current-carrying coil of a hypothetical rectangular field of length L. The variable parameters of the electrostatic lens are the voltage ratio and the separation distance while in the magnetic lens the variable are the Ampere-turn and lens length. The combined electrostatic and magnetic lens (Gabor lens) has been investigated under zero and infinite magnification conditions. The paraxial ray equation has been solved with the aid of the axial electric and magnetic potential distribution using Runge-Kutta method. The axial potential and its first and second derivatives have been used for computing the optical properties of the lens under consideration. The lens spherical and chromatic aberration coefficients have been normalized in term of the focal length under zero and infinite magnification conditions.